How water insects bounce on water without sinking revealed

A research team in South Korea has reportedly reached very close to revealing the secret behind the water strider's baffling ability to bounce up and down on water without sinking.

Their findings will be significant because they may facilitate the development of robots that can move about on lakes and reservoirs to monitor water quality, spy or explore.

The researchers are expected to reveal their findings in the forthcoming issue of the journal Langmuir.

Ho-Young Kim and Duck-Gyu Lee of Seoul National University have revealed that the research team has already discovered how the water-repellent, hairy structure of the water strider's legs enable them to scoot along ponds and placid lakes.

For solving the mystery of how the insects "bounce" off liquid surfaces, the researchers dropped a highly water-repellent sphere onto the surface of water at different speeds, and carefully tracked its motion with high-speed cameras.

Upon analysis of the footage, they construed that the ball might be travelling within a narrow range of velocities in order to bounce off the water's surface.

They said that the sphere might sink if it went too fast, and would not bounce back if it was too slow.

Dr. Kim said that the finding revealed why water striders have extremely water repellent legs, and how they touch down at just the right speed not to sink.

"Application of our study can be extended to developing semi-aquatic robots that mimic such insects having the surprising mobility on water," the Telegraph quoted Dr. Kim as saying.

The newspaper report says that some water striders can propel their bodies across the water surface at nearly 3.5 feet per second, which is 100 times their body length.

The insects are able to skim around on water because water molecules at the surface are strongly attracted to each other and those beneath, unlike the air above. This leads to surface tension, a skin-like effect that such insects exploit.

According to the researchers' calculations, says the paper, the strider's legs can support 15 times the insect's weight without it sinking. (ANI)

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